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Search filters_
| Filter | Wind energy | Photovoltaic energy | Biomass energy |
|---|---|---|---|
| Document type | Articles | Articles | Articles |
| Search in Subject área | Title, abstract or keywords | Title, abstract or keywords | Title, abstract or Keywords |
| Years | 2005–2019 | 2005–2019 | 2005–2019 |
| Search terms | “wind energy” AND “renewable energy | “solar energy” OR “photovoltaic energy” AND “renewable energy” | “biomass energy” AND “renewable energy |
Minimum frequency of words occurrences_
| Period | Wind energy | Photovoltaic energy | Biomass energy |
|---|---|---|---|
| 2005–2007 | 3 | 4 | 3 |
| 2008–2010 | 5 | 7 | 3 |
| 2011–2013 | 5 | 7 | 3 |
| 2014–2016 | 5 | 8 | 3 |
| 2017–2019 | 6 | 10 | 4 |